Pipe coupling



FIG. 1 is a perspective view of the pipe coupling;

FIG. 2 is a view of the front of the pipe coupling;

FIG. 3 is a view of the back of the pipe coupling; and,

FIG. 4 is a view of the top of the pipe coupling, where the bottom of the pipe coupling would be a mirror image. 

The ornamental design for a pipe coupling, as shown and described. 